Twineham is a small parish in the low Weald that is bounded by Shermanbury to the west, Bolney to the north and north east, Woodmancote to the south and Hurstpierpoint to the south and east. The main settlement is the small village of Twineham, that lies on Twineham Lane and the access road to the church. To the north is the hamlet of Twineham Green on the road to Bolney and to the east is Hickstead, another hamlet, on the old A23 crossroads. On Wineham Lane to the west, which forms the parish boundary with Shermanbury, is the hamlet of Wineham, with those houses on the eastern side of the road belonging to Twineham. The landscape is one of low ridges punctuated by watercourses running east to west. Open fields predominate and there is little woodland. Much of the settlement is scattered farms, though the six in operation during the 1970s has now been reduced to one.

The current A23 runs through the eastern edge of the parish and now bypasses the old crossroads at Hickstead. However, running through the centre and forming the spine of the parish is an old north-south droveway, that links High Cross to Crosspost south of Bolney. The southern part up to the junction with Hickstead Lane is Twineham, that to the north is Bolney Chapel Road. Three roads branch off this highway, Church Lane at Twineham leads to the school and church before continuing westwards as a footpath. Hickstead Lane runs eastwards to the old crossroads at Hickstead. Lastly, Bob Lane meanders westwards from Twineham Green to Wineham Lane. The north eastern part of the parish boundary runs along Pookbourne and Stairbridge Lanes whilst the entire western boundary runs up the middle of Wineham Lane. Another highway, Gratten Lane, once linked twine ham Lane with Wineham Lane via Great Wapses Farm, but has been reduced to a bridleway.

Twineham's name derives from its location, 'the place between two waters', the two waters in this case being the eastern branch of the River Adur and one of its tributaries, Herrings Stream. Both waterways run across the parish from east to west. At Hooker's Bridge to the north once stood Hooker's Mill, originally built as a watermill but when that proved problematic with water flow added a windmill to help power it.

Twineham's small size means it lacks services, there were once two post offices, one at Twineham and one at Hickstead, but these are long closed. It still possesses its school, opened in 1864 in a former tithe barn. There was a pub at Hickstead, the Castle Hotel, later Inn, which once served travellers on the old London-Brighton turnpike, it is now a Chinese restaurant. The turnpike itself later became a trunk road which in the early 1990s was realigned to bypass the old crossroads at Hickstead, however, the new junction provided an ideal spot for services and thus a filling station, Travelodge and Little Chef appeared, the latter replacing a former building demolished when the new A23 was built.